1. Field of the Invention
The present invention relates to a connecting device for electrically connecting an electric vehicle to a battery-carrying trailer and/or an off-board electric supply system.
2. Description of Related Art
The accumulator batteries used in electric vehicles have to be periodically recharged from an electricity power grid through appropriate connecting devices. Conductive type of devices similar to household plugs have been in use, but are relatively cumbersome to handle, that is, to align mating parts and then pull them apart against a fitting-friction connection. Additionally, there are risks of possible electrical shock to operators. An inductive type of connector device has been suggested for transferring electric energy by way of electro-magnetic waves which provides easier handling and safety, but only in exchange for higher costs.
Neither type of connector provides a specific safety mechanism against any accidental pulling apart of the mating connections, which is the kind of precaution needed in the case of supplying off-board electricity from a battery-carrying trailer to electric vehicles as described, for instance, in U.S. Pat. No. 5,559,420, where two vehicles are in motion together. The evaluation of electric vehicles and the ability to rescue a disabled electric vehicle subject to a power shortage, by mechanically attaching an auxiliary battery-carrying trailer, is becoming more necessary inasmuch as Ground Positioning System and telecommunication technology have been developed to show where help is needed as well as when help is available.
However, an electric vehicle should have a receiving port at its tail-end because the source of electricity supply is to be towed behind it. Many conventional electric vehicles have their recharge ports normally positioned at the front of the vehicle, and it would be generally impractical for an electric vehicle to have two separate ports. In addition, a battery-carrying trailer itself requires recharging by a commercial power grid. Thus, the prior art is still seeking an efficient and economical solution to these issues.